not to kick a horse that has been dead and rotted for 20+ years but srvs tone was more than any one thing.  yes he used a tube screamer, yes he used heavy strings, and big amps and blah blah blah.  he sounded like him with pretty much any setup.  he did use a tube screamer but not just a ts808 or ts9, he also used the ts10 which no one seems to think is worth much.  from what ive read from his tech, he got boxes of single strings from ghs.  hed use 11s, 12s, and 13s depending on how his hands were feeling and his 13 set wasnt much different from my custom 11 set i used to use other than the high e (13, 15, 19, 28, 38, 58  vs 11, 15, 19 ,28, 38, 54), i think tuning down a 1/2 step is a bigger part of his sound.  trying to say any one thing was the secret to srv's tone if foolish unless you are talking about his hands.